1. Field of the Invention
The present invention relates to a prop-type damping device which converts up-and-down vibration caused by earthquakes, winds, passing vehicles and the like on a main girder of a bridge such as an elevated bridge into horizontal displacement by a tip of a prop-shaped member, and consumes displacement energy thereof by a damper to reduce the up-and-down vibration of the main girder.
2. Description of the Related Art
A structure is deformed upon reception of external forces by earthquakes, winds, passing vehicles and the like to store energy therein. With this energy the structure causes next deformation therein to keep balance. If this energy is consumed before the next deformation occurs, it is possible to reduce the deformation of the structure. For example, a main girder of a bridge for a road, a railway or the like is vibrated up and down upon reception of the external forces from earthquakes, winds, passing vehicles or the like. If energy of such up-and-down vibration which occurs on the main girder is consumed, a life of the bridge can be prolonged, and comfort for bridge users can be greatly improved.
Meanwhile, as a damping device for damping up-and-down vibration of a floor structure of a building, there has conventionally been known a damping device which arranges a viscoelastic plate between a steel plate and a connection plate facing thereto, adheres both surfaces of the viscoelastic plate to the steel plate and the connection plate, fixes the steel plate to a center side face of a beam for supporting the floor, connects the connection plate to mutually proximate higher ends of two straight members inclined in reverse-V shapes, fixes mutually separate lower ends of the straight members to lower support members under girths for supporting both ends of the beam, accordingly fixes the connection plate to framing of the building to prevent vibration of the connection plate with the floor, and absorbs energy of the up-and-down vibration of the floor by up-and-down shearing deformation of the viscoelastic plate.(e.g., see Japanese Patent Laid-Open No. 2002-70228).
However, If the damping structure that fixes the connection plate by the two straight members inclined in reverse-V shapes to prevent up-and-down vibration thereof is applied to the main girder of the bridge, since an effective span distance of the main girder of the bridge is generally very long the straight members become extremely long to nearly lose inclination. Consequently, it is very difficult to fix the connection plate to prevent up-and-down movement thereof for practical purposes.